Star Classification on the H-R Diagram Astronomy

Name______________________

Directions: 1. Open the freeware program HRC-20.exe 2. Either plot the star manually using the data below. Or, go to File operations and import the star by name and Apply to the H-R diagram. Note its location (a cross hair) and record its classification (what group it belongs to). 3. Click on Info and record data in the table provided. Observe the size of the star compared to our sun and solar system. 4. If the program quits, just restart it and continue where you left off. 5. Complete the second data table as you plot each star. Star Sirius Procyon Arcturus Vega Capella Rigel Betelgeuse Altair Aldeberan Spica Antares Deneb Castor Pollux Polaris Distance from Earth (in pc) 2.63 3.5 11.0 7.67 12.58 429 429 4.9 18.4 67.5 160 460 15 12.0 110.4 Apparent Magnitude -1.46 0.38 -0.04 0.03 0.08 0.12 0.50 0.77 0.85 0.98 0.96 1.25 1.57 1.14 1.97 Temperatur e (K) 10,400 6,800 4,500 10,700 5,900 11,800 3,200 8,000 4,200 21,000 3,400 9,900 9,150 4,900 6,150 Absolute Magnitude +1.4 +2.6 -0.3 +0.6 +0.4 -8.1 -7.2 2.3 -0.3 -3.2 -5.2 -7.2 0.5 +0.8 -3.2

For the distance in light years, you will have to calculate using the distance in parsecs. The rest of the information on this table is obtained from the graph. The questions below refer to both tables. Read them carefully.

Star

Calculate the distance in light years (from parsecs)

Spectral Type (O,B, A, etc.)

Classification (what group on the H-R diagram?)

Compared to sun (How many times the solar radius?)

Sirius Procyon Arcturus Vega Capella Rigel Betelgeuse Altair Aldeberan Spica Antares Deneb Castor Pollux Polaris

1. 2.

From the list of stars, which is the most luminous? And, to what group does it belong on the HR diagram? To what group does our Sun belong on the HR diagram? How does it compare to other stars?

3. From the list of stars, which is the least luminous? And, to what group does it belong on the HR diagram? 4. From the list of stars, which is the brightest in the sky? And, to what group does it belong on the HR diagram? 5. From the list of stars, which is the hottest star? And, to what group does it belong on the HR diagram? Explain why the most luminous star is not necessarily the brightest star in the sky.

6.